Conventionally, there exists a system in which image forming apparatuses, such as printers, copying machines, and multifunction machines, and computers are interconnected through a network.
FIG. 24 is a block diagram showing an example of the configuration of a conventional network system including conventional image forming apparatuses, which is used by a plurality of users under a network environment, for example.
In FIG. 24, the network system is comprised of a plurality of personal computers PC 1103a, PC 1103b, copying machines 1101a, 1101b, and a server 1102, which are interconnected through a network. The copying machines (both of the copying machines 1101a, 1101b) are each comprised of a printer section 1201, a reader section 1216, a controller section 1202, and a DC power supply 1203. The controller section 1202 controls exchange of information with external devices, the ON/OFF of the DC power supply 1203, and the operations of the reader section 1216 and the printer section 1201.
When a copying operation or a printing operation has not been carried out for a predetermined time period, the copying machine 1101a (1101b) shifts into a sleep mode (an energy saving mode, a reduced power consumption mode) so as to save energy (electric power consumption).
Further, by installing an application software program for managing the network in the PC 1103a (1103b), it is possible to know the status of the copying machine 1101a (1101b) connected to the network. For example, when the copying machine has run out of paper, this software program enables the PC to display the status of the copying machine thereon. Even if the copying machine 1101a or 1101b is in the sleep state, when a print request is transmitted from the PC 1103a or 1103b connected to the network, the controller section 1202 within the copying machine having received the print request detects the print request and starts the DC power supply 1203 to energize the entire copying machine to execute print output.
However, the above described network system according to the prior art suffers from the following problem:
When an image forming apparatus, e.g. a copying machine, connected to the network is in the sleep state, and receives from a PC an inquiry about the latest status of the copying machine whose status is updated as occasion demands, the controller section 1202 activates the DC power supply 1203 to supply electric power to all engines of the copying machine, and then communicates with the reader section 1216 and the printer section 1201 so as to detect the inquired status, whereafter the result of the detection is transmitted to the PC via the network.
Therefore, even though the copying machine is in the sleep state where energy conservation is being achieved, it is necessary to supply electric power to the entire copying machine whenever the status of the copying machine is inquired, or alternatively, the copying machine needs to constantly hold all the engines in energized states without shifting to the sleep mode, which is contradictory to the recent trend toward energy conservation.